1. Technical Field
The present invention relates to a heavy-load tire possessing improved bead durability achieved by effectively preventing CBU (Cord Broken Up) of carcass cords that pass near the bead core on the axial inner side of the tire.
2. Related Art
FIG. 5 shows a typical structure of the bead portion on a conventional heavy-load tubeless type tire. The bead portion usually includes a bead core “b” of metallic wire extending in a ring shape along the tire circumference, a carcass ply “c” of a steel cords turned around the bead core “b”, and a bead reinforcing layer “d” of steel cord with an L-shaped cross section arrayed along the carcass ply “c”. See Japanese Patent Application Publication No. 2002-205508.
Heavy-load tires with this type of bead portion structure are used under severe conditions including heavy loads and high internal pressures, causing the carcass cords to rupture or cord broken up (hereinafter simply referred to as “CBU”). The present inventors found that CBU occurs frequently on the bead core “b” on the axial inner side of the tire.